1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
|
///////////////////////////////////////////////////////////////////////////////////
// Copyright (C) 2012 maintech GmbH, Otto-Hahn-Str. 15, 97204 Hoechberg, Germany //
// written by Christian Daniel //
// //
// This program is free software; you can redistribute it and/or modify //
// it under the terms of the GNU General Public License as published by //
// the Free Software Foundation as version 3 of the License, or //
// //
// This program is distributed in the hope that it will be useful, //
// but WITHOUT ANY WARRANTY; without even the implied warranty of //
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the //
// GNU General Public License V3 for more details. //
// //
// You should have received a copy of the GNU General Public License //
// along with this program. If not, see <http://www.gnu.org/licenses/>. //
///////////////////////////////////////////////////////////////////////////////////
#include <QTime>
#include <stdio.h>
#include "nfmdemod.h"
#include "audio/audiooutput.h"
#include "dsp/dspcommands.h"
MessageRegistrator NFMDemod::MsgConfigureNFMDemod::ID("MsgConfigureNFMDemod");
NFMDemod::NFMDemod(AudioFifo* audioFifo, SampleSink* sampleSink) :
m_sampleSink(sampleSink),
m_audioFifo(audioFifo)
{
m_rfBandwidth = 12500;
m_volume = 2.0;
m_squelchLevel = pow(10.0, -40.0 / 20.0);
m_sampleRate = 500000;
m_frequency = 0;
m_squelchLevel *= m_squelchLevel;
m_nco.setFreq(m_frequency, m_sampleRate);
m_interpolator.create(16, m_sampleRate, 12500);
m_sampleDistanceRemain = (Real)m_sampleRate / 44100.0;
m_lowpass.create(21, 44100, 3000);
m_audioBuffer.resize(256);
m_audioBufferFill = 0;
m_movingAverage.resize(16, 0);
}
NFMDemod::~NFMDemod()
{
}
void NFMDemod::configure(MessageQueue* messageQueue, Real rfBandwidth, Real afBandwidth, Real volume, Real squelch)
{
Message* cmd = MsgConfigureNFMDemod::create(rfBandwidth, afBandwidth, volume, squelch);
cmd->submit(messageQueue, this);
}
void NFMDemod::feed(SampleVector::const_iterator begin, SampleVector::const_iterator end, bool firstOfBurst)
{
Complex ci;
bool consumed;
for(SampleVector::const_iterator it = begin; it < end; ++it) {
Complex c(it->real() / 32768.0, it->imag() / 32768.0);
c *= m_nco.nextIQ();
consumed = false;
if(m_interpolator.interpolate(&m_sampleDistanceRemain, c, &consumed, &ci)) {
m_sampleBuffer.push_back(Sample(ci.real() * 32768.0, ci.imag() * 32768.0));
m_movingAverage.feed(ci.real() * ci.real() + ci.imag() * ci.imag());
if(m_movingAverage.average() >= m_squelchLevel)
m_squelchState = m_sampleRate / 50;
if(m_squelchState > 0) {
m_squelchState--;
Complex d = ci * conj(m_lastSample);
m_lastSample = ci;
Real demod = atan2(d.imag(), d.real()) / M_PI;
demod = m_lowpass.filter(demod);
demod *= m_volume;
qint16 sample = demod * 32767;
m_audioBuffer[m_audioBufferFill].l = sample;
m_audioBuffer[m_audioBufferFill].r = sample;
++m_audioBufferFill;
if(m_audioBufferFill >= m_audioBuffer.size()) {
uint res = m_audioFifo->write((const quint8*)&m_audioBuffer[0], m_audioBufferFill, 1);
/*
if(res != m_audioBufferFill)
qDebug("lost %u samples", m_audioBufferFill - res);
*/
m_audioBufferFill = 0;
}
}
m_sampleDistanceRemain += (Real)m_sampleRate / 44100.0;
}
}
if(m_audioFifo->write((const quint8*)&m_audioBuffer[0], m_audioBufferFill, 0) != m_audioBufferFill)
;//qDebug("lost samples");
m_audioBufferFill = 0;
if(m_sampleSink != NULL)
m_sampleSink->feed(m_sampleBuffer.begin(), m_sampleBuffer.end(), firstOfBurst);
m_sampleBuffer.clear();
}
void NFMDemod::start()
{
m_squelchState = 0;
}
void NFMDemod::stop()
{
}
bool NFMDemod::handleMessage(Message* cmd)
{
if(cmd->id() == DSPSignalNotification::ID()) {
DSPSignalNotification* signal = (DSPSignalNotification*)cmd;
qDebug("%d samples/sec, %lld Hz offset", signal->getSampleRate(), signal->getFrequencyOffset());
m_sampleRate = signal->getSampleRate();
m_nco.setFreq(-signal->getFrequencyOffset(), m_sampleRate);
m_interpolator.create(16, m_sampleRate, m_rfBandwidth / 2.1);
m_sampleDistanceRemain = m_sampleRate / 44100.0;
m_squelchState = 0;
cmd->completed();
return true;
} else if(cmd->id() == MsgConfigureNFMDemod::ID()) {
MsgConfigureNFMDemod* cfg = (MsgConfigureNFMDemod*)cmd;
m_rfBandwidth = cfg->getRFBandwidth();
m_interpolator.create(16, m_sampleRate, m_rfBandwidth / 2.1);
m_lowpass.create(21, 44100, cfg->getAFBandwidth());
m_squelchLevel = pow(10.0, cfg->getSquelch() / 20.0);
m_squelchLevel *= m_squelchLevel;
m_volume = cfg->getVolume();
cmd->completed();
return true;
} else {
return false;
}
}
|
